Zambian chamber choir sings Byrd

Peter Phillips writes that "Last week Byrd’s Mass for Four Voices was heard in concert — I assume for the first time — in Lusaka, Zambia." The group is Vox Zambezi, which sings many styles but Phillips was particularly drawn to its performance of Byrd, partly because it shatters the pervasive tendency to regard this polyphony as somehow bound up with European experience only.

Browsing around I found this short clip of the group singing some piece of polyphony, and I bet one of the readers could name it immediately. I don't recognize it, and I'm sure I'll shortly be embarrassed to admit it.

(Thanks IanW)